Rudius 1911 80 Percent Frame

A site I regularly visit had a blog post about this today. If I understand correctly, since the frame is only 80% complete you can buy it and finish it yourself without an FFL or serial number. I have never heard of this before, is this common? Has this been tested legally?

This has got to be the ultimate TacHacker project. Ares Armor is offering the Rudius 1911 80 Percent Frame. Named after the wooden sword presented to a Roman Gladiator upon earning his freedom. Fitting name once you understand what Ares has in mind

Due to the level of finish on the weapon, it is not yet a weapon. According to Ares Armor, To complete this frame all that need be done are the slide rails, barrel seat and the two rear pin holes. THERE IS NO FFL REQUIRED PER BATFE SPECIFICATIONS. This is not a firearm until you decide to make it one. Now, the Rudius 1911 80 Percent Frame is available for pre-order at a significant discount.

They have a YouTube video on their site.

I am not connected to this company, just curious about the product and its legal status.